This invention relates generally to evaporators adapted to convert liquified gas into a heated gas, and more particularly to a gas evaporator incorporating a heat pipe to transfer heat from an external source to the interior of a pressure vessel.
Though the invention is applicable to the evaporation of various forms of liquified gas, such as ammonia and sulfur dioxide, it will be explained in connection with chlorine, for this gas is widely used in water purification, sewage treatment, and in many industrial processes.
Chlorine evaporators of the type commercially available, make use of a chlorine chamber supported within a larger water chamber having an immersion heater therein. One such evaporator is manufactured by the Fischer & Porter Co. of Warminster, Pa., the device being described in their Instruction Bulletin for the MOdels 71V1006 and 71V1008 Chlorine Evaporators.
In this known type of evaporator, the water heated in the water chamber provides a uniform distribution of heat around the outer surface of the chlorine chamber. As a result, liquid chlorine fed into the chlorine chamber through an inlet pipe, absorbs heat from the water chamber through the wall of the chlorine chamber, causing the liquid chlorine to boil and converting it into a superheated gas which is discharged through an outlet pipe.
One of the drawbacks encountered in this known type of evaporator resides in its poor heat transfer characteristic in that the heat from the heater must be conducted through the water bath and then through the wall of the chlorine chamber. Also because the chlorine chamber is immersed in heater water, the wall of the chlorine chamber is subject to corrosion, further degrading the conditions of heat transfer. Moreover, high operating temperatures are required, giving rise to high heat losses and accelerated rates of corrosion.
A further disadvantage of an existing type of evaporator is that it requires a reasonably pure water supply and plumbing from the evaporator to the supply as well as water temperature and flow controls, thereby complicating the installation and adding to the costs thereof.